Engine starter



0a. 22, 1929. R, ABE'LL 'ET AL 1,732,294

. ENGINE STARTER Filed June 16, 1928 I 2 Sheets-Sheet 1 2 INVENTORS.

ATTO E Oct. 22; 1929. R. ABELL ET AL ENGINE STARTER Film; June 15. 1928 2 sheets -sheet 2 I INVEIVTORS.

M ar' w A110 EYB Patented Oct. 22, 1929 UNITED STATES PATENT OFFICE ROLLIN ABELL, OF MILTON, MASSACHUSETTS, AND JOE N CRAWFORD, OF DETROIT, MICHIGAN; SAID CRAWFORD ASSIGNOR, BY MESNE ASSIGNMENTS, TO SAID ABELL ENGINE STARTER Application filed June 16,

This invention relates, in its broader aspects, to an automatic coupling device adapted to be functionally interposed between a rotary driving member and a rotary member to be driven and .operative to automatically engage and drive the member to be driven upon rotation of the driving member and to automatically disengage said driven member upon rotation of the latter at a speed in excess of that of the driving member.

The coupling herein illustrated and described is more particularly designed for use as an automobile engine starter and embodies features to be hereinafter pointed out, which more nearly fulfill all of the exacting requirements of engine starting in present day motor cars. However, it is apparent that the present coupling may be employed with substantially equal advantage for engine starting generally or in any situation where similar conditions and requirements exist.

Fundamentally, the present invention aims to simplify the construction and improve the character of service and operation of automatic drive couplings of the type indicated.

More particularly, the invention is concerned with improvements in a coupling or engine starting unit of a type known in the art as the pinand cam slot type.

One such improvement resides in a construction and arrangement of the pin and cam slot such as to produce a rapid and unfailing engagement of the coupling member with the driven member and thereafter a positive drive.

One object of major importance is to provide a coupling of this type which will not be susceptible to the conditions which commonly cause premature disengagement; another major object is to provide a starter which will function in such manner that after initial engagement of the driving with the driven member, for the purpose of eflecting starting of the engine has been made, the said engagement will be maintained until the engine has been definitely started and set into normal continued operation, thus obviating the difficulties and disadvantages now present in many starters in which the driving element may disengage from the driven one 1928. Serial No. 285,902.

"regardless whether or not the engine is normally set in operation under its own power. It is obvious that such improved mode of functioning reduces the number of times the driving member must necessarily be engaged with the driven member to bring about start-' ing in the event the engine fails to promptly motor by merely closing the usual starting switch without bringing about a repeated meshing and demeshing of the driving pinion with the gear driven thereby, the same remaining in mesh after being initially engaged until the engine is finally placed in normal continued operation.

Another object is to provide a couplingof this type which shall be capable of withstanding the eflects of an engine backfire without having its operative condition disturbed.

A further object of this invention resides in the provision of yielding means for holding the'parts of the coupling in normal inoperative position and for preventing undesired movements or rattling thereof.

Other objects of the invention relate to details of construction, design and arrangement of elements, all conducive of low production cost and prolonged satisfactory operation.

A preferred embodiment of this invention is illustrated'in the drawings, wherein,

Fig. 1 is a view in side elevation of a coupling embodying our invention, the flywheel or other driven memberbeing shown in section,

' Figs. 4 and are views inlongitudinal sec tion, with portions in elevation, showing the parts in positions corresponding to Figures 7 1 and 2, respectively, and

Figs. 6 and 7 are views in transverse section'taken on lines 6-6 and 7 7, respectively,

I of Figure 1.

notwithstanding these'many advantages and the existence of operative devices of this general type in the prior art, there has not been devised, prior'to the present invention, a coupling of this type which has satisfactorily met the exacting conditions of commercial use as an engine starter, The practical im perfections of the various known forms of the pin and cam slot type of coupling are eliminated by the construction of the present invention. The features of this construction and the particular problems to which they are a solution may be more fully understood from the following detailed description.

In Figures 1 and 2 is shown the relative location of a conventional starting 'motor 1 and .flywheel or other driven element2. The motor has an extended armature shaft 3 which, as shown in Figures 4 and 5, is formed with a shoulder 4 and an extended portion 5 of reduced diameter. This armature shaft supports and has operative connection with the automatic coupling unit which will now be described.

On the extreme outer end of the reduced portion 5 of the armature shaft is fitted a collar 6 which is removably secured to the shaft in a convenient manner as by means of a longitudinalkeyway 7 in the collar, a key 8 and a key seat 9 in the shaft. In order to prevent axial separation of the collar and shaft, a set screw 10 and lockingring 11 are employed in the manner clearly illustrated 1 Vin Figure 5. The inner end of the collar is provided witha pair of diametrically opposed radiallyexteneling pins 12 which may be formed integral with the sleeve as shown or otherwise as desired. A sleeve 13 surrounding the armature shaft has an axial bore of proper diameter to aflord a free sliding support upon the enlarged portion 3 of the shaft and intermediate its ends the sleeve is formed with a radial web 17 having a bore of. proper diameter to provide a free sliding support upon the reduced portion 5 of the shaft. There is thus provided a two point support between the shaft and sleeve. Extending rearwardly from the sleeve 13 and preferably integral therewith is an enlarged sleeve 15 having an internal axial bore of slightly greater diameter than that of collar 6. This extension sleeve loosely surrounds the collar 6 and is formed with opposed cam slots 16, the form of which is clearly shown in Fig. 2, for reception of and coaction with the radial pins 12 in a manner to be hereinafter explained. The opposite end of sleeve 13 i formed with pinion teeth 14 for coaction with the driven member 2 in a manner which will also be hereinafter explained.

Disposed within the bore of sleeve 13 and between shoulder 4 and web 17 are two independent coil springs 18 and 20, respectively, of relatively different strengths, spring 18 siderably larger than the shaft and its outer surface is spherically rounded whereby to permit free tilting or rocking movements without binding in order to automatically ac- I commodate itself to the movements and conditions of the springs. The light spring 18 is of a diameter to seat within the cupped portion ofmember 19 and the heavy spring 20 seats against the bottom of this member. The opposite ends of springs 18 and 20 seal; against the web 17 and shoulder 4, respectively.

The construction of the cam slots 16, heretofore briefly mentioned, is a major feature in importance 1n this IIIVGIItIOII. Referring to Figures 1, 2, and 2*, it will be observed that i the cam slots, which are generally designated by the reference numeral 16, are each formed with a closed end 21 in which the pins 12 normally rest and a pin receiving pocket 22 wherein the pins seat when the part of the coupling are in power transmitting condition. Each pocket 22 is formed with a straight wall 24 parallel to the axis of the shaft, which walls form positive driving abutments for .the pins 12. Projections or bumps 23 separate the pockets 22 from the cam slots proper, whereby to oppose free movements of the pins from the cam slots into the driving pockets and vice versa. Thecam slots proper are of differential pitch, that is, they progressively increase in degree of curvature from 'the closed ends 21 outwardly toward the open ends. The purposes and operation of this and other features of my improved pin and cam slot construction will be made to clearly appear in the outline of operation hereinafter given.

. Operation :In the A normal non-driving condition of the parts as represented in Fig ures 1 and 4, the pinion 14 is disposed in its outermost position on the armature shaft and the ring gear or toothed portion of the flywheel occupies a plane closely adjacent the end of the pinion and intermediate the latter and the starting motor. The parts are maintained in this condition while the motor is inoperative primarily by means of the light spring 18 which also serves to keep the coupling tight and to prevent vibration and rattling thereof. Upon energization of the starting motor and consequent high speed rov tation of the armature shaft the pinion 14 is advanced toward the motor and into initial meshing engagement with the teeth 20 of the flywheel. The beginning of this first stage of action results from the coaction of pins 12 and cam slots 16 due to the inertia of sleeve 13 and the consequent lagging of the sleeve relative to the rapidly rotating shaft. Owingto the differential pitch of the cam slots, the

force exerted by the pins onthe walls of the slots during this first stage of axial advance- 'ment is composed of an initial relatively great axial component and a relatively small rotary I component, the former progressively decreasing and the latter progressively increasing throughout this first stage of advancing movement. From this it follows that the speed of this axial movement increases and the force decreases progressively from the start. On completion of this first stage of 'movement, the pinion occupies a position intermediate the positions illustratedln Fig-- ures l and 2, respectively, with the light spring 18 fully compressed and the cup member 19 in engagement with the web 17. 'At this time the pins 12 occupy positions in cam slots 16 slightly below the humps or projections 23. During the second or final stage of I action the sleeve 13 moves axially against the tension of the heavy spring 20 and the pins ride over thehumps 23 and seat down into the depressions or pockets 22. The pinion and flywheel are now in fully engaged position and the pins engage the straight walls- 24 of the pockets, thus providing a'positive and unyielding driving connection from the armature shaft to the flywheel.

Considerable difiiculty has heretofore been experienced with many different types of engine starters in maintaining the starting pinion in driving engagement with the flywheel until the engine becomes fully self operative. This difliculty is due in a large measure,i not entirely, to the impulsive action or accelerative effect of an internal combustion engine due to the pistons passing from high to low compression zones. It also arises due to an occasional firing in the engine cylinders before the engine becomes fully self opera tive. This acceleration is often sufficient to cause an undesired disengaging movement of the starting pinion before the engine becomes self propulsive. Another difficulty heretofore experienced and. pertaining more particularly to the pin and cam slot type of engine' starter is that of undesired separation of the pin and cam slot elements occasioned by a back fire of the engine. 'Much damage is likely to result fromsuch a separation of these elements. The present invention embodies features of construction which entirely obviate these difiiculties.

The trouble just mentioned, namely, that of premature disengagement of the pinion, is entirely obviated, and the engagement between the driving pinion and driven gear thereby interposing additional force against 1 removal of the pins from their pockets. Owing to the enhanced resistance thus opposed to the unmeshing action, premature disengagement of the coupling such as previously described is prevented. However, when the flywheel assumes normal operation under power of its engine there is established suflicient torque to cause relative movement between the pinion sleeve and the armature shaft which positively withdraws the pins from their pockets even against such en-' hanced resistance, causing the pins to ride over the humps or projections into and along the cam slots until the pinion is entirely disengaged from the flywheel.

. It is apparent that certain difficulties above referred to are eliminated by the provision of the straight walls 24 parallel to the axis of the coupling. It should be understood that in couplings of this general type, disengagement of the pinion from the flywheel is effected by rotation of the pinion in the same direction as but at a'greater speed than the armature shaft while the effect of'a backfire of the engine is to' rotate or thrust the pinion reversely with reference to the direcf tion of. rotation of the armature shaft. In

the ordinary cam slot construction this reverse thrust would embody an axial component sufficient to cause complete axial separation of the .pins and cam slots. In fact, it has been found that a pin engaging wall slightly inclined to the shaft axis is sufficient to cause this undesired action. In the present construction the longitudinal component of the reverse thrust is entirely elimiwith the shaft axis. Thus, there is no possibility of the parts of the present coupling becoming separated and causing noise or damage. I

The features of the present invention which constitute it a distinct advance in the engine starter art should be readily understood and their merits appreciated by those familiar with this art in view of the foregoing description and. the accompanying drawings.

Notwithstanding that the improvements constituting the present invention are, as to structure, to some extent of a detailed nature, they are nevertheless fundamental as regards the operating characteristics essential to successful commercial use. In this connection it may be stated that devices constructed in strict accordance with this invention have successfully withstood extensive practical tests and as a result have gone into wide commercial use. For these reasons, it is to be understood that the invention is not limited to the precise details of construction shown, but embraces a wide range of equivalents by which the fundamental characteristics herein disclosed may be achieved. It should also be understood that the essential characteristics of the invention may be embodied in' structures differing widely from that herein illustrated as regards the manner of use,

respect thereto. the movement of said driving member with respect to said shaft operating to engage the same with and disengage the same from said driven member and the movement of said driving member with said shaft operating to drive said driven member, means connecting said shaft and driving member for effecting such movements,

- said means embodying coacting cam elements associated with the shaft anddriving member respectively and constructed and arranged to interpose a substantial resistance to the disengaging movement of said driving member, whereby to prevent premature disengagement of the driving-and driven member.

2. A coupling, comprising a rotatable driving shaft, a rotatable member to be driven disposed in proximity to said shaft, a driving member supported by said shaft and adapted for movement therewith and with respect thereto, the movement of said driving member with respect to said shaft operating to engage the same with and disengage the same from saidv driven member and the movement of said driving member with said shaft operating to drive said driven member, means connecting said shaft and driving member for efl'ecting such movements, said means embodymg a pin and. cam

slot connection between said shaft and driving member,-said cam slot terminating in straight wall parallel, to the axis of the shaft whereon said .pin bears during a driving operation, whereby the force transmitted between said pin and wall in either direction of rotation is free of longitudinal components.

3. 'A coupling comprising a rotatable shaft, a-drivingmember mounted on said shaft for rotary movement therewith and longitudinal movement thereon, coacting camvelements associated with said member and shaft for efl'ecting such movements, one of said cam elements embodying means adaptedto coact with the other said ca element to oppose the longitudinal movement of said member in one direction.

24. A coupling comprising a rotatable element, a driving member supported by said ro- .tatable element for rotary and longitudinal sliding movements, a driven element disposed adjacent said rotatable element and adapted under certain conditions to beengaged and driven by said driving member and under other conditions to reverse the flow of power and drive said driving member, a cam slot formed in one of said members, a pin carried by the other said member and coacting with said slot whereby rotation of said rotatable element operates to advance said driving member into engagement with said driven element and the rotationof said driving mem ber by said driven element at a speed in excess of that of the rotatable element operates to withdraw said driving member from engagement with said driven element, yieldable means for opposing a resistance to the longitudinal engaging movement of said driving member, and means associated with said cam and cooperating with said yieldable means to oppose the initial disengaging movement of said driving member whereby to prevent premature disengagement.

5. A coupling comprising a rotatable ele ment, a driving member supported by said rotatable member for rotary and longitudinal sliding movements, a driven element disposed adjacent said rotatable element and adapted under certain conditions to be engaged and driven by said driving member and under other conditions to reverse the flow of power and drive said driving member, a cam slot formed in one of said members, a pin carried element and the rotation of said driving member by said driven element at a speed in excess of that of the rotatable element operates to withdraw'said driving member from engagement with said driven element, yieldable means for opposing a resistance to the longitudinal engaging movement of said driving member, and means associated with said cam and cooperating with said yieldable means to oppose the initial disengaging movement of said driving member whereby to prevent premature disengagement, said yieldable means tending to produce disengaging movement of said driving member after the initial disengagement has been effected.

6. An engine starter drive comprising a power shaft, a driving member mounted on said shaft for rotary and axial Sliding-move-' ments, said driving member havlng a cam slot formed therein, onewall of said cam slot being provided with a shouldered pocket, a radially extending pin secured for rotation with said shaft and projecting into said cam slot for coaction therewith, whereby relative rotation of said shaft and driving -member operates to move said driving member axially in one or an opposite direction and-to place said pin in driving relation with said pocket or to remove the same therefrom.

7. An engine starter drive comprising a "power shaft, a driving member mounted on said shaft for rotary and axial sliding movements, said driving member having a cam slot' formed therem, one wall of said cam slot being provided with a shouldered pocket, a radially extending pin secured for rotation with said shaft and projecting into said cam slot for coaction therewith,whereby relative rotation of said shaft and driving member operates to move said driving member axially in one or an opposlte direction and to place said pin in driving relation with said pocket or to remove the same therefrom, an abutment associated with said shaft, yieldable means interposed between said abutment and said driving member and operative to resist the movements of said pin into and from saidshouldered pocket. I

8. A coupling of the type described comprising a rotatable shaft, a driving member mounted on said shaft for rotary and axial sliding movements, said driving member being formed with a cam slot and a driving pocket, a pin projecting from said shaft and adapted to traverse said cam slot whereby to effect the said axialsliding movements of said driving member and adapted to engage said pocket for effecting the said rotary movement of said driving member.

9. A coupling of the type described comprising a rotatable shaft, a driving member mounted on said shaft for rotary and axial sliding movements, said driving member being formed with a cam slot and a driving pocket, a pin projecting from said shaft and described comprising a rotary shaft, a driving member rotatably and slidably mounted on said shaft, an engine member disposed adjacent said shaft, and adapted to be engaged and driven by said driving memberfa pin and cam slot connection-between said shaft and driving'member, whereby rotation of said shaft effects axial movement of said driving member into engagement with said engine member and rotation of said driving member by said engine member at a speed in excess of that of the shaft effects the movement of said driving memberout of engagement with; said engine member, said cam slot having a' driving wall thereof provided with a straight shoulder parallel to the axis of said shaft, whereby the rotary thrust between said pin and slot when the parts are in operative position is without longitudinal components irrespective of the direction of such thrust.

11. In a device of the character described,

' the combination with a member of an engine on said shaft, a plurality of springs of different relative strengths operatively interposed between said abutment; and driving member, and an operative connection between said shaft and driving member whereby relative rotative movement between said shaft and driving member will cause axial sliding movement of the driving member upon said shaft.

12. In a device of the character described, the combination with a member of an engine to be started, of a shaft disposed adjacent to said member and operatively associated with a source of power, a driving member mounted on said shaft for rotary and axial sliding. movements and adapted to engage, drive, and disengage said engine member, an abutment on said shaft, a plurality of springs of different relative strengths operatively interposed in serial relation between said abutment and drivin member, a cup-like member interposed etween and affording a seat for the adjacent ends of said springs and adapted to completely house one of said springs when fully compressed and'to then directly abutsaid driving member, and an operative said member and operatively associated with j a source of power, a driving member mounted on said shaft for rotary and axial sliding movements and adapted to engage, drive, and disengage said engine member, an abutment on said shaft, a plurality of springs of different relative strengths operatively interposed in serial relation between said abutment and driving member, the relative strengths of said springs being such that one'thereof becomes compressed efore any substanital compres sion of the other takes place, means interposed between the adjacent ends of said springs for transmitting force directly to said other spring after said one has become fully compressed, whereby to prevent distortion of said compressed spring and means assdciated with said shaft and driving member for effecting automatic engagement and disengagement between'the latter and said engine member.

14. In a device of the character described, the combination with a member of an engine to be started, of a shaft disposed adjacent said member and operatively associated with a starting motor, said shaft having a relatively short section of large diameter adjacent said motor and a relatively long section of small diameter extending outwardly therefrom with a' shoulder dividing the said sections,

a driving member in the form of a sleeve surrounding sa1d shaft, said sleeve havlng a bore of a diameter to afford a sliding support upon the shaft section of large diameter, an inwardly directed radial flange formed on said sleeve and constituting an end wall of said sleeve bore, said flange having an axial opening of proper diameter to afford a sliding support upon theshaft section of small diameter, yield'able means disposed within said bore and interposed between said shoulder and flange and means connecting said shaft and driving member and cooperating with the said yieldable means for automatically actuating said driving member into and out of engagement with said engine member.

I 15. An engine starter drive comprising a power shaft, a driving pinion rotatably and slidably mounted on said shaft, operative connections between said shaft and pinion whereby relative rotative movement therebetween will cause said pinion to travel longitudinally of said shaft, means for temporarily automatically and resiliently locking said pinion against return longitudinal movement in one direction after *said pinion reaches a redetermined position on said shaft, said ocking means being operative to release said tures.

ROLLIN ABELL.

JOHN CRAWFORD. 

